Extensive research and development have been made in various fields of technology in order to automate the judgment of a particle coagulation pattern in a clinical test of blood, etc.
For example, there is already proposed one system in which an automatic judgment of a coagulation pattern is performed in an optical way in a blood test apparatus. Diffusion light from an LED (light emitting diode) is irradiated onto a transparent microplate which is provided with a plurality of reaction vessels for coagulating blood therein, and the light transmitted through the microplate passes through a lens system and is detected by a plurality of CCD line sensors disposed adjacent a lower surface of the microplate. This microplate is mechanically movable, thereby enabling the system to read, one after another, images showing the states of coagulation of blood dropped into the plurality of reaction vessels disposed on the microplate in different testing bodies. The images are converted into the form of electronic signals by the CCD line sensors.
In such blood testing apparatus as mentioned, owing to limitation of the length of each CCD sensor with respect to the size of the microplate, images of coagulation patterns are read using a plurality of CCD sensors. As a method for driving the CCD sensors used in such case, there was contemplated a parallel driving method, in which a plurality of CCD sensors (a system employing three CCD sensors is reviewed here) are simultaneously driven.
FIG. 6 is a timing chart for explaining the conventional CCD driving method. In this driving method, three CCD sensors (CCD1, CCD2 and CCD3) are simultaneously driven in parallel, and the output of each of the three CCD sensors is gradually read. In FIG. 6, the time from ST to END indicates the shortest reading time, and the mark X indicates the fact that data are discarded while output of the remaining CCD sensors is being read.
In general, the light accumulation time which the CCD requires for obtaining an effective CCD output waveform (gain) is very long compared with the time (effective output time) required for the CCD to generate an output corresponding to the number of elements which the CCD has. That is, the time required for optically sensing the image is much longer than the subsequent time required for converting the optically sensed image into an output electronic signal (i.e., output data).
The total time required for reading the output of the three CCDs in the parallel driving method of FIG. 6 is [light accumulation time .times.2+Effective output time] at minimum, even if it is presumed that the timing for starting the reading can be suitably selected and the sequential order for the reading is not fixed. Thus, it inevitably becomes a very inefficient method.
The present invention aims at solving such problem inherent in the prior art.
The object of the present invention is to provide, in a CCD driving method using a plurality of CCD sensors, the capability of shortening the time required for reading the outputs from the plurality of CCD sensors, thereby enhancing efficient processing of CCD output signals.
The present invention is directed to a CCD driving circuit for reading and outputting data from a plurality of CCD sensors, and includes driving means which drives the CCD sensors such that the driving times of said CCD sensors are staggered so that the effective output times of said CCD sensors will not overlap each other, and data read from each of said CCD sensors are multiplexed by multiplexing means and then output. Accordingly, the time required for reading the outputs from a plurality of CCD sensors can be shortened compared with the conventional parallel driving method.